The Friday File: Families with teens are expected to spend about $1,078 on prom festivities based on several surveys. In the Northeast, the average will be $2,000, in the South, $1,047 and in the West and Midwest, $744 and $696 respectively. Interestingly, expected spending is higher the poorer you are. Families earning between $20,000 and $30,000 will, on average, spend (hold your breath) over $2,600; high income bracket families will spend, on average, $850.